The present invention generally relates to optical fibers and more particularly, to an apparatus for arranging a plurality of coated optical fibers in a predetermined plane and a collective fusion splicing method using the apparatus, in which the coated optical fibers are collectively fusion spliced and reinforced.
Since optical fibers have been utilized for public communication, there is, at present, a keen demand for rationalization and facilitation of removal of coating from coated optical fibers and cutting and fusion splicing of the coated optical fibers in manufacture of optical fiber cables.
Conventionally, in order to join optical fibers permanently, a fusion splicing method is widely employed in which the optical fibers are joined with each other through fusion thereof by heat of aerial discharge.
In response to recent increase of quantity of optical transmission, multi-fiber optical fiber cables each having multiple coated optical fibers have become necessary. To this end, there are a ribbon type multi-fiber optical fiber cable in which a plurality of coated optical fibers 1 are collectively formed into a ribbonlike shape as shown in FIG. 1a and a loose tube type multi-fiber optical fiber cable in which a plurality of the coated optical fibers 1 are inserted into a tube 2 at random as shown in FIG. b.
In the ribbon type multi-fiber optical fiber cable, since it is possible to collectively perform removal of coatings of the coated optical fibers 1 and cutting and fusion splicing of the coated optical fibers 1, the manufacturing processes are simplified and the production cost is reduced, thereby resulting in rationalization and facilitation of joining of the coated optical fibers 1. Meanwhile, in the loose tube type multi-fiber optical fiber cable, the coated optical fibers 1 are joined one by one by using a single-core type fusion splicing apparatus. Thus, in view of recent trend of the multi-fiber optical fiber cables for increase of the number of the coated optical fibers 1 up to 600-3,000 in response to expansion of capacities of optical transmission lines, the loose tube type multi-fiber optical fiber cables have such a drawback that a time period required for joining the coated optical fibers 1 increases further.
Meanwhile, a technique for fusion splicing a plurality of the coated optical fibers 1 collectively and a technique for fusion splicing a plurality of the coated optical fibers 1 of the loose tube type multi-fiber optical fiber cable with those of the ribbon type multi-fiber optical fiber cable collectively have not been developed so far.
FIGS. 2a and 2b show a known method of joining the coated optical fibers 1. As shown in FIGS. 2a and 2b, the coated optical fibers 1 accommodated in a multi-fiber optical fiber cable 3 are separated from one another in the vicinity of an end of the cable 3 and glass portions 4 of the coated optical fibers 1 are fusion spliced with corresponding ones of the opposite coated optical fibers 1 individually, respectively such that joints 5 of the glass portions 4 are produced. Each of the joints 5 is reinforced by a reinforcing member such as a heat-shrinkable tube 6. The heat-shrinkable tube 6 contains hot-melt adhesive 8 in which a reinforcing core 7 is embedded.
However, the known joining method has such disadvantages that since a number of the coated optical fibers 1 are joined with each other individually, its operation is quite troublesome and time-consuming and that the joints 5 become large in size.